Below are the changes for the current release.
See the CHANGES file for changes in older releases.
See the RELEASENOTES file for a summary of changes in each release.
Issue # numbers mentioned below can be found on Github. For more details, add
the issue number to the end of the URL: https://github.com/swig/swig/issues/

Version 4.0.1 (in progress)
===========================

2019-06-28: wsfulton
            [MzScheme, OCaml] #1559 $arg and $input were incorrectly substituted in the
            argout typemap when two or more arguments were present.

2019-06-24: wsfulton
            [Python, Ruby] #1538 Remove the UnknownExceptionHandler class in order to be
            C++17 compliant as it uses std::unexpected_handler which was removed in C++17.
            This class was intended for director exception handling but was never used by
            SWIG and was never documented.

            *** POTENTIAL INCOMPATIBILITY ***

2019-06-06: bkotzz
            [Java] #1552 Improve performance in Java std::vector constructor wrapper that takes
            a native Java array as input.

2019-06-03: olly
	    [Python] Fix regression in implicit_conv handling of tuples,
	    introduced in SWIG 4.0.0.  Fixes #1553, reported by Alexandre
	    Duret-Lutz.

2019-05-24: wsfulton
            [Octave] Fix detection of Octave on MacOS.

2019-05-24: opoplawski
            [Octave] #1522 Adapt OCTAVE_LDFLAGS for Octave 5.1.

2019-05-22: ferdynator
	    [PHP] #1528 Don't add a closing '?>' PHP tag to generated files.
	    PSR-2 says it MUST be omitted for files containing only PHP.